Chassay Last were employed alongside structural engineering consultancy Symmetrys Limited, to provide innovative structural and civil engineering design to deliver Eglon House. The striking new work/live residence in Primrose Hill, London, was inspired by Pierre Chareau’s iconic Art Deco Parisian architectural Masterpiece ‘Maison de Verre’. The site was previously The Mayfair Studio where famous artists such as Tina Turner and Pink Floyd recorded platinum selling albums, before being converted as part of a £6m contract for developer Fairfax Partners.
Detailed and designed to the highest standards, the striking four storey modern property echoes the design philosophy of Maison de Verre. Pioneering structural engineering solutions including ‘top down’ construction were devised and implemented to overcome tough site constraints, including delivering the project within the confines of existing perimeter walls that landlocked the site. Key elements of the building’s structure are purposely left exposed adding to its architectural splendour and echoing a key feature of Maison de Verre’s design, which centred around honestly displaying materials and mechanical fixtures.
Additional factors that Symmetrys placed at the heart of delivering Eglon House included an efficient construction programme, minimising disruption to local residents, and sustainability.
The original structure of the Mayfair Recording Studio was three storeys high. Perimeter walls were built from masonry which were restrained at roof level by agricultural trusses. The site was effectively landlocked on all four sides by the perimeter walls of neighbouring properties which restricted access and raised challenges as they could not be encroached upon during the redevelopment.
An array of design techniques and options were reviewed, but to minimise disruption to neighbouring properties, and to ensure the site remained accessible at ground level it became clear that the rarely used ‘top down’ construction method was the most appropriate solution. Contiguous piles were installed very close to the boundary walls in order to form new perimeter basement walls and build from the ground up while the basement was simultaneously being cut.
Chris Atkins, Symmetrys managing director explained: “The top down construction method maintained site access to the constrained site throughout the works due to the ground slab being in place - this would not have been the case with a traditional open cut solution. Structural movement to neighbouring properties was also minimised because the ground slab acted as a permanent prop that prevented movement to neighbouring properties during construction. In addition, the method ensured that work was not carried out underneath the boundary walls of surrounding properties, minimising disruption to them.”
With the most viable solution decided, Symmetrys worked with the architect to set the proposed ground level at a height that prevented any undermining of the perimeter walls following the installation of the perimeter pile cap/beams and ground slab. The ground slab was specially designed to accommodate an increased imposed load of construction traffic for when it was in a temporary condition. Symmetrys therefore gave careful consideration to the temporary location of the sacrificial plunge piles and set out their location for the contractor. This is key to successful top down construction, where thought must be given to how the structure behaves in both a temporary and permanent condition.
With the temporary piles and the ground slab in place the basement could be cut via a large void in the ground slab, while the superstructure was simultaneously erected from the ground floor level up. This significantly sped up the construction programme. Careful thought was given to formwork layouts on the underside of the ground floor slabs so quality concrete finishes could be exposed in the completed structure, echoing the design of Maison de Verre. Once the ground floor was cast the basement cut commenced through the permanent double height void and the superstructure was erected at the same time.
Chris Atkins commented: “Top down construction bought significant economic benefits to the delivery of Eglon House. The construction period was reduced dramatically when compared with traditional underpinning methods, due to the simultaneous construction of the basement and the superstructure. This was of particular importance on this high end project where material and design costs were high – efficiencies in the construction process was one area where savings could be made.”
To ensure disruption to the local community was diminished the agricultural roof of the existing structure was retained for as long as possible during the construction process to minimise dust and noise pollution. Even when work began on the final storey of the property the roof was maintained for this purpose.
Structures Echoing Maison de Verre and Maximising Architectural Splendour - Designed in 1932 Maison de Verre was hailed as a landmark in early modern architecture. A primary reason for this was its displays of exposed framework, industrial and mechanical fixtures under the transparency of its façade. The honesty of building materials and the variable transparency of forms was a key feature. Eglon House reverberates this philosophy through the transparency of its structure which provides the building’s main aesthetic.
Symmetrys designed steel columns and concrete soffits to be intentionally exposed both internally and externally clearly displaying the property’s mechanics, while polished concreate slab floors are another notable feature. Maison de Verre was an early pioneer of the work/live trend with commercial space on the ground floor and residential accommodation above. Eglon House alludes to this by being divided into two distinct structures that face off across a courtyard and are linked together at basement level. One side has an industrial character for work while the other is more domestic.